A method and a device for adapting tolerances of a transmitter wheel is known from, for example, German Patent No. 41 33 679 (U.S. Pat. No. 5,428,991), which describes a method and a device for adapting mechanical tolerances of a transmitter wheel. The transmitter wheel has a plurality of approximately equidistant marks which are sensed by a pickup supplying a pulse train on the basis of which measured values are formed.
Because of tolerances in the manufacture and installation of the transmitter wheel, the markings are not always equidistant. Therefore, means are provided for these tolerances to be learned and taken into account. To do so, the individual measured values are compared with a reference value. A certain measured value is used as the reference value.
With this procedure, only tolerances assuming the same value in all operating states can be compensated. However, tolerances which have different values in different operating states usually also occur.
The manufacturing tolerances of the transmitter wheel have almost the same effect in all operating states. However, torsional vibration of the shaft on which the transmitter wheel is arranged depends on the operating state. As a result, these tolerances cannot be adequately compensated with the procedure according to the related art.
In addition, German Patent No. 195 27 218 describes a method and a device for controlling the smooth operation of an internal combustion engine. With this device, correction values for the quantity of fuel to be injected are determined on the basis of measured values of a segmented wheel to perform a cylinder equalization. This should achieve the result that the same quantity of fuel is metered to all cylinders. To do so, the speed signal is analyzed. Irregular speed suggests the occurrence of irregular injection, which is corrected accordingly.
Transmitter wheel tolerances result in uneven speeds of the individual segments, although the quantity of fuel injected is uniform. When the above method is used, the speed is regular but the quantity of injected fuel differs from one cylinder to the next.